A typical engine block for a reciprocating piston, internal combustion engine comprises two general portions; the crankcase portion and the cylinder portion. The crankcase portion is generally configured as a cavity that is configured to support a rotating crankshaft while the cylinder portion includes cylinder walls that are generally surrounded by a water jacket through which engine coolant is circulated under pressure for the purpose of removing excess heat therefrom. Once the engine coolant is circulated through the cylinder water jacket it may be diverted to another portion of the internal combustion engine, such as the cylinder head, to remove additional excess heat or it may be pumped to a heat exchanger where heat is removed from the coolant prior to being returned to the engine.
An important consideration in the design of the cylinder portion of the engine block is the efficient distribution and flow of the coolant for maximum effectiveness as well as for the avoidance of thermal inconsistencies that may induce warping or deflection of the block or cylinder head causing damage to, or poor performance of, the internal combustion engine. Coolant entering the water jacket from an external source requires careful flow direction to assure that it fully circulates through and around the cylinder portion.